An analyst now says that the CEO's sudden departure is a clear sign that the firm is in "disarray."

The reasons Greubel's resignation caused a stir are big problems:

UBS' biggest shareholder GIC supported Gruebel's staying on to manage the crisis according to Reuters: "GIC's support of Gruebel until the very end also shows that while his leaving may have satisfied some shareholders, it hardly reassured the Singapore fund, which owns 6.4 percent of the bank... "GIC believed he had good plans," a source told Reuters.

Two big management positions are now filled by relative new-comers. His sudden departure suggests a worrying level of disorder, especially as Chief Financial Officer Tom Naratil took up his post only three months ago, an analyst for Mediobanca, Christopher Wheeler.

The departure and the scandal are causing morale, already low, to crash.

Morale within the investment-banking division, already depressed following the trading scandal, dropped even further in the wake of Gruebel's departure, according to an executive at the unit who requested anonymity because he wasn't authorized to speak publicly.

According to the report, the board unsuccessfully attempted to persuade Gruebel to stay until the investor's day meeting in New York on November 17, where he was set to announce major changes to the investment bank division.

Gruebel thinks it was the best decision.

"That it was possible for one of our traders in London to inflict a multibillion loss on our bank through unauthorized trading shocked me," he said in a memo adding that the scandal was a "major setback" for UBS's efforts to rebuild trust.

The real problem now might be convincing i-bank head Carsten Kengeter to stay on. Reports suggest that UBS was considering how to scale down the size of its investment bank under Gruebel.

The former CEO had pushed for an 'integrated bank" model which meant investment bank would be part of the business. The source said the investment bank could help facilitate the core wealth management business of the Swiss bank.

Now the future of the ibank is unclear. Kengeter, the head, is faced with political challenges from the Swiss government, where UBS is headquartered and based. The Swiss are pushing for higher capital requirements on its banks, which make stem the profitability of ibanks.

He and interim chief executive Sergio Ermotti are now tasked with how to deal with UBS's investment banking business to satisfy both investors and regulators, as the FT reported.

And of course, the bank has a new chief financial officer, Tom Naratil, who's been in his post for only about three months.

And to add to the already low morale, UBS still faces thousands of layoffs.

UBS has already announced 3,500 job losses across the group, about half of which will fall within the 17,700-person strong investment bank. A more credible number is closer to 10,000, several analysts said, which means 5,000 in additional job losses in a business already suffering from rock-bottom morale.